Just like all the other authenticated APIs in the world: you get a token when you log on, and use that token to authenticate yourself on future calls to the ser

Just like all the other authenticated APIs in the world: you get a token when you log on, and use that token to authenticate yourself on future calls to the services. That's a lot of what OAuth and its ilk handle. This management of API boundaries is likely handled for you by an app, though, so from a user perspective the story is still "open netflix, enter password, watch movie".